Electronic portable devices such as laptops, tablet personal computers (PCs), smart phones and other products are increasingly used in daily life. Some of the electronic components employed by these electronic devices generate thermal energy (heat) during operation, which, in order for the device to operate properly, must be dissipated. In this regard, a cooling module or a heat sink, in the form of, e.g., a cooling fan, a heat pipe, or a two-phase siphon cooling system (or two-phase thermosiphon cooling system) may be incorporated inside the electronic device to assist in dissipating excess heat.
The heat dissipation efficiency of a heat conductive sheet or heat pipe is limited, however, so a cooling fan is often employed in combination therewith. However, the operation of a cooling fan relies on power provided by a battery of the electronic device, leading to increased consumption of that limited battery power. While some electronic devices have been designed with a two-phase siphon cooling system, such a system typically requires a fluid to circulate in a pipeline as a result of a difference of potential energy (height) and the gravitational force among the fluid molecules. When the relative state between the electronic device and the gravitational direction changes, the efficiency of such a cooling system decreases.